Entomologists of the Division of Plant In-
dustry, Florida Department of Agriculture,
provide an identification service for the State
of Florida of insects, mites, spiders, scor-
pions, millipedes, centipedes, and other ar-
thropods. Spiders, particularly, seem to
arouse the curiosity of many people who
submit specimens for identification and re-
quest control recommendations. Like the
snakes, spiders are little understood and
Such maligned by most people, usually with
little or no justification. So far as known,
with the exception of the members of two
ssmall families, all spiders have poison
i glands. The venom is used to kill their prey
and as a means of defense. However, only a
few species, such as certain tarantulas and
other spiders of the tropics, produce avenom
virulent enough to be harmful to man. More-
over, most species are too timid and do not
attempt to bite even when handled roughly.
In Florida, only the spiders belonging to the
Group commonly called widows are capable
of inflicting a bite serious to man. The bite
of the larger wolf spiders and the fearsome
looking silk spider is little worse than the
Sting of a bee or wasp. Most other native
spiders seldom bite man, and many are in-
Scapable of doing so.
While the incidence of bites by widow
spiders is not high, the widow spiders are

fairly common in Florida, and questions
regarding them are received frequently by
the entomologists of the Division of Plant
Industry who curate the Florida State Collec-
tion of Arthropods. The seriousness of the
bite of a mature female widow spider sug-
gests that the general public should be cor-
rectly informed concerning this group of
spiders, including their prompt recognition
and the treatments recommended for bites.
The Widow Spiders of Florida is the sec-
ond in an irregularly appearing series of
publications relating to the insects and other
arthropods of Florida and neighboring land
areas-the southeastern United States, the
Bahama Islands, the Greater and Lesser An-
tilles, and the land areas in and round the
Gulf of Mexico-with emphasis on taxonomy,
ecology, biology, and zoogeography. Empha-
sis in this series, initiated early in 1965 with
the publication of Lepidoptera of Florida by
C. P. Kimball, is on the Florida fauna.

Introduction: There are four species of the
black widow genus Latrodectus that are
known to occur in Florida: the southern
black widow, Latrodectus mactans (Fabri-
cius); the northern black widow, L. various
Walckenaer; the red widow, L. bishop Kas-
ton; and the brown widow, L. geometricus
C. L. Koch. Since the immatures and the
adult male Latrodectus do not pose a public
health problem, descriptions in this publica-
tion are limited to the mature females. Males
cannot be identified to species easily.
The Genus: The spiders in this genus are
fairly large, the overall length with legs ex-
tended is about 11/2 inches. They have a
small cephalothorax and a large, high,
smooth, subglobose abdomen. Although the
whole body is densely covered with short
almost microscopic hairs, the spiders have a
shiny naked appearance. Some of the charac-
ters used to separate the species are difficult
to see without a microscope and special tech-
niques. When possible, specimens should be
captured and placed in a vial or bottle of
70% alcohol, such as rubbing alcohol, and
submitted for positive identification by a
specialist. Fortunately, however, in Florida
it is possible to identify most adult female
specimens by means of their distinctive color
patterns.

LATRODECTUS MACTANS, The Southern
Black Widow

Identification: The body is glossy black to
sepia. The dorsum of the abdomen is usually
free of markings, although occasionally there
are remnants of the immature color pattern.
There is a red hourglass marking on the ven-

ter of the abdomen and a red spot on the
posterior end of the abdomen just above
the spinnerets.
Distribution: This is the most widespread
species of the genus in Florida. It has been
taken in most counties and probably occurs
in all of them. The other species have more
limited distributions.
Habitat and Life History: The southern
black widow occupies a large variety of habi-
tats, usually near human habitation or in
newly disturbed areas. It makes an irregular
web of very tough silk in such protected
places as stumps, discarded pipe and build-
ing materials, under stones, in storm sewers
and water meter boxes, and under park
benches and tables. It is seldom found in
houses in Florida. Connected to the web is
a small silken retreat. In Florida, this spider
has no well defined breeding cycle, and all
stages of development can be found at any
time. The females make several egg sacs
during an extended period after mating.
These egg sacs are pear-shaped to almost
globular, and the tough papery outer cover-
ing ranges in color from white to tan. Each
sac contains from one hundred to several
hundred yellowish eggs. Often these eggs
have been parasitized either by dipterous or
hymenopterous egg parasites. In addition to
parasites, the main factors limiting popula-
tion size are extreme climatic conditions
such as extremely high or low humidity and
freezing.

LATRODECTUS VARIOUS, The Northern
Black Widow

Identification: This species has the same
general appearance as L. mactans. It differs
in that there is a median longitudinal row
of red spots on the dorsum of the abdomen,
and on the venter there are two transverse
red bars instead of an hourglass.
Distribution: In Florida, L. various has
been found only west of Tallahassee. It is

particularly abundant in the vicinity of Tor-
reya State Park.
Habitat and Life History: The northern
black widow is found in mesic and xeric
hammocks where the adults make webs in
the branches of trees. These webs occur in
a range of 3-20 feet off the ground. A dome-
shaped retreat is located in the leaves at the
end of a branch, and treads radiate out to
one or more branches. Unlike L. mactans,
L. various has a well defined breeding cycle.
During March and April, immature spiders
are widely scattered in forest litter, and in
late spring, adults are found in the trees.
Mating occurs and the males die immediately
afterward. During the summer, adult females
are found in the retreats with one or more
egg sacs which are similar to those of L.
mactans. By late fall all adults are gone, and
very small immatures are found in the forest
litter.

LATRODECTUS BISHOP, The Red Widow

Identification: The cephalothorax and legs
are reddish orange. The entire abdomen may
be black, or may have dorsal median red
spots or dorsal red spots surrounded by a
yellow border, while the venter, lacking a
complete hourglass, may have one or two
red spots.
Distribution: This species has a very re-
stricted distribution. It has been found only
in sand-pine scrub associations in central
and southeastern Florida.
Habitat and Life History: The red widow
almost always makes its web off the gound
in palmettps in sand-pine scrub. The web
retreat is made by taking a palmetto frond
and rolling it into a cone. The interior of
the cone is lined with silk and the egg sacs
are hung from the sides of the cone. The
egg sacs are light gray to white in color and
have a fairly soft outer covering unlike the
papery covering of L. mactans and L. vari-
olus. The threads of the web spread from
frond to frond of the palmettos and form a
sheet-like pattern. Adults are found all year.

LATRODECTUS GEOMETRICUS, The Brown
Widow

Identification: This species varies in color
from light gray to light brown or even al-
most black. The dorsum of the abdomen has
a highly variable pattern consisting of black,
white, red, and yellow markings. On the
venter is an hourglass which is orange or
yellowish red in color.
Distribution: L. geometricus is cosmotropi-
cal. It probably was introduced into Florida
and is most abundant in coastal cities in the
lower part of the peninsula, but a few have
been found as far north as Daytona Beach.
Habitat and Life History: The brown wid-
ow is quite abundant in some of the coastal
cities of southeastern Florida. It usually
makes its web on buildings in well lighted
areas. Service stations are particularly good
places to find them. The webs are somewhat
like those of L. mactans but are smaller,
while the silk is not as tough and the web-
bing is very dirty and unkempt. The egg
sacs appear very different from those of
other Latrodectus sp. Instead of being
smooth, the outside of the egg sac is covered
with little papules. Adults are found all year,
and there does not seem to be any definite
breeding cycle.

Medical Importance

All four species have very potent venoms,
but for a variety of reasons, only L. mactans
is likely to be involved in a spider bite case
in Florida. If an individual is bitten by one
of the other species, the same measures
recommended for L. mactans bites should
be taken.
The bite of L. mactans produces a sharp
pain similar to a needle puncture. Usually
this pain disappears rapidly, but it may per-
sist for hours. Local muscular cramps are
felt 15 minutes to several hours after the
bite. The muscles most frequently affected
are those in the thigh, shoulder, and back.
Later severe pain spreads to the abdomen,
and there is weakness and tremor. The ab-
dominal muscles show a boardlike rigidity.

Respiration becomes spasmodic, and the pa-
tient is restless and anxious. During this
period a feeble pulse, cold clammy skin,
labored breathing and speech, light stupor,
and delirium may be noted. Convulsions,
urinary retention, shock, cyanosis, nausea
and vomiting, insomnia, and cold sweats also
have been reported.
Local measures, such as those used for
snakebite, do not seem to be effective be-
cause the venom spreads very rapidly. Medi-
cal treatment should be sought immediately,
and the patient should be kept quiet and
placed in bed as soon as possible. One vial
of Lyovac antivenin should be administered
to patients under 14 years of age. The acute
pain of the muscle spasms may be relieved
by prolonged warm baths, hydrotherapy, or
the intravenous injection of 10% calcium
gluconate. Recently, intravenous injection
of 10 ml of methocarbamol (Robaxine) over
a 5-minute period, followed by slow intra-
venous drip of the drug in sodium chloride,
has proved to be very effective.
Death may occur from the venom, depend-
ing upon the victim's physical condition,

age, and the location of the bite. Complicat-
ing factors such as syphilis, heart disease,
and/or kidney disease coupled with the ven-
om may produce a fatality. Adults are more
resistant to poison than children, but indi-
vidual sensitivity may enhance or depress
the reaction of both age groups. The only
case on record of a healthy adult being
killed by the venom is one in which the vic-
tim was bitten at the base of the skull, there-
by giving the brain a potent and rapid dose
of venom.

Control

Spiders and egg sacs may be crushed with
a broom, and any debris that harbors the
spiders should be cleared away. Five to 10%
DDT or 2% lindane can be used to control
these spiders. BHC used in closed areas at
the rate of 1/6 oz. of the product per 130 cu.
yds. is the most effective insecticide. Treat-
ment should be repeated after 30 days to
destroy any broods which have emerged.